Valve devices of this type for medical instruments are used, for instance, in trocars. Trocars are used for inserting operating instruments for endoscopic operations, for instance into the abdominal cavity of a patient. For this purpose the trocar sleeve is placed on the abdominal surface, a trocar pin is inserted into the hollow instrument channel, an opening is made in the abdominal surface with the help of the trocar pin, and then the trocar sleeve is inserted into the abdominal area through the opening. The trocar pin can then be withdrawn again from the trocar sleeve.
Because it is common, with endoscopic operations of the abdominal area, to fill the abdominal area with gas for expanding the operating space and forming a pneumo-peritoneum, the hollow instrument channel of the trocar sleeve can be closed with a valve body so that the gas cannot escape from the abdominal area by way of the trocar sleeve when the instrument is removed. Valve bodies known in the art are configured in such a way that they are opened by an instrument that is inserted into the instrument channel and then close again independently when the instrument is removed.
A generic valve device for a medical instrument, namely a trocar, is known for instance from DE 297 00 762 U1. In this known trocar, the rotation axle that supports the valve body is configured as a U-shaped arched wire spring, by which the valve body is pre-tensioned in the closed position. The free ends of the spring are bent inward at a right angle at various points and secured in the housing in bore-holes arranged at intervals from one another. Because of the various lengths of the strands of the spring, the rotating of the valve body causes a tensing of the spring, so that it pressures the valve body in the direction toward the closed position. The configuration of the bore-holes for inserting the free ends of the spring makes it necessary to respect narrow tolerance values, so that the manufacture becomes labor-intensive and thus expensive. In addition this known valve device is very difficult to clean.
It is consequently the object of the invention to design a valve device for medical instruments of the aforementioned type in such a way that it is of simple, cost-effective construction and can easily be cleaned. The fulfillment of this object according to the invention is characterized in that the rotation axle is configured in several components, such that the individual components of the rotation axle can be connected to one another by means of helical-shaped guide tracks.